The present invention relates generally to solid waste separators and more particularly to those utilizing a flow of pressurized air through a duct structure separating non-homogeneous waste by density, such separators being termed air classifiers and used primarily at municipal waste disposal sites.
Existing classifier prior art, to the extent known, includes chutes or ducts of zig zag configuration through which an upward flow of air travels with waste being injected into the chute. Waste particles so injected are imperfectly separated into but two general categories, light and heavy fraction which require further classification such as by running same through a second air classifier. A serious problem exists in separating out lighter fraction such as waste paper, wood fragments and other organic materials. Common practice entails the use of multiple zig zag chutes.
Particle or fraction size and shape are additional factors in air classifying. Granular particles have a tendency to collect within vortices within the chute airflow and migrate downwardly along boundary areas adjacent chute walls. This results in recycleable material, such as waste paper being lost by reason of being improperly mixed with heavier waste fraction. Conversely, a problem exists in the mixing of glass splinters with paper fragments.
As the value of reclaimed waste is largely determined by the accuracy with which separation is accomplished, imprecise air classifying results in the loss of material which otherwise could be recycled. As the sale of reclaimed paper and other cellulose matter brings a sizable return to the disposal site operator, such a loss is highly undesirable.